August 2, 2011

Temperatures are on the whole lower on Areios and combined with lower levels of oxygen means that all organisms on Areios are limited by these conditions. The aliens we find on this world are not towering monsters; Areiosans are tiny by comparison to their Terroan cousins. The largest animals on Earth are creatures like sequoias or blue whales, but Areiosans pale in comparison to this. The largest Areiosans are about the size of a horse. Clonal colony organisms like honey mushrooms and coral reefs however, are a different story. On Earth, aspen trees are a conglomerate of root systems that some ecologists argue could be construed as a single organism. Areiosans have much more surface area to sprawl out, more wide open spaces to colonize. The immense gravity keeps them down though. One wouldn’t find anything resembling a giraffe on Areios; most creatures heed gravitropism on Areios, growing outward not upward. Fungi cover huge swaths of Areiosan continents, filling up niches usually afforded to moss or lichens on Earth. And the oceans are just as teeming with life; purple and red algae blanket the surface of oceans, tinting the seas blood-red. These algae colonies are the lifeblood to all animal life because they serve as the organisms on the planet to replenish oxygen by virtue of the dearth of plant life on Areios. Their origin paves the way for animal life to evolve later on.

The first algae don’t appear on Areios until there is enough sunlight penetrating the lower atmosphere to support photosynthesis. The smog of the Areiosan atmosphere blocks most of Hemera’s light from breaking through, but as the star brightens, it begins to overcome the hazy atmosphere and penetrate to the surface of the planet. The first algae descended from aquatic organisms floating on the surface of oceans, eating the iron dissolved in the water. When the faint slivers of ultraviolet light broke through the atmosphere, it would cause die-offs of the surface protists. A mutation in a gene that coded for a membrane protein changed the function of a surface protein, allowing it to transmit and reflect light instead of absorbing it, acting like a sunscreen. Channeling those ultraviolet photons outside of the cell, this novel protein is of benefit to these protists because they no longer risk exposure to dangerous ultraviolet rays. This rudimentary sunscreen is the first step towards building photosynthesis on Areios.

Plants on Earth are fine-tuned to utilize the light coming from the Sun, which means that plants transmit mostly red and yellow light while green light bounces off the pigments and into our eyes, which is why we plants as green. But these colors are only specific to plants on Earth, which are calibrated to maximize the amount of energy they can extract from the light from our Sun. But on another planet, a different Sun would put out a different range of the visible light spectrum more than our Sun and this would mean that plants on those planets would reflect a different color on the spectrum and we could see plants that range from jet-black to silvery-white and any color in between. On Areios, there are no plants because sulfur dioxide withers cellulose and burns the chlorophyll pigments plants use. While algae possess a unique bacterial form of chlorophyll, they are not true plants. The only way to run photosynthesis on Areios is within the insulating environment of the ocean. Photosynthetic algae on Areios have to rely on the dim light from Hemera, so photosynthesis on this planet relies on yellow and green light, so instead algae have a dark blue-violet color to help their pigments absorb light.

Over time, mutations accumulated in this population that led to the appearance of very basic mechanism for electrons to pick up the photons that strike its surface. With successive generations cells evolved more efficient ways to pick up photons and ferry them outside the cell. Somehow in piecemeal additions to the mechanisms of these cells, the photons that once were an occupational hazard for these surface-dwelling protists became a source of fuel for future populations; these photons got gobbled up by electrons and passed like a game of hot-potato through the cell membrane of these protists. Those electrons became a currency for a metaphorical toll booth that allowed protons passage out of the cell. These protons carry a positive charge and there is a charge gradient when you compare the inside of the cell with the outside of cell. But protons would not ordinarily want to move outside of the cell, and so special proteins embedded within the cell have to facilitate the movement of protons outside of the cell. This movement of protons across the cell membrane of a protist is called the proton motive force that fuels ATP synthesis.

On our world, plants appear green, but not this need not be the case; planets orbiting different stars could host different-colored plant life